The present invention relates to a display device; and, more particularly, to a driver and a driving method therefor capable of displaying various desired patterns by dynamically driving display elements including matrix-shaped dots and multiple display segments.
A display device having fluorescent electrodes as its display elements displays a variety of information in a form of characters or graphics or a combination thereof by appropriately controlling the fluorescent electrodes and driving, e.g., grid electrodes in accordance with the characters or graphics or the combination thereof to be displayed thereon.
A matrix pattern incorporated in the display device is constructed with anodes used as the fluorescent electrodes and with grids used in controlling electrons arriving at the anodes, the anodes and the grids being activated by a dynamic driving method, wherein pulse signals are in a time-shared manner, thereby enabling the display device to display rather complicated graphics and characters or the combination thereof with a reduced number of wires.
In addition to the above, it is also possible to dynamically display a large quantity of time varying information on a screen by scrolling the graphics or the characters or the combination thereof in an appropriate direction especially when the anodes are dot-shaped.
FIG. 12 represents a block diagram of a conventional display device for use in, e.g., a variety of electronics equipments and machines, for displaying various information such as operating information, time information, etc. The display device includes drivers capable of visualizing various information provided by display data from a host micom (micro-computer) storing therein control program of the equipments.
In FIG. 12, a reference numeral 10 represents a VFD(vacuum fluorescent display), composed of, e.g., vacuum fluorescent tubes. Generally, electrodes in the VFD are structured such that various graphics or characters or the combinations thereof are displayed using segmented electrodes and dot-shaped fluorescent elements.
An anode driver 20a and a grid driver 20b serve as the driving circuits for activating anodes and grids of the VFD 10, respectively. These drivers 20a and 20b generally include therein switching elements being switched on and off by control pulses, shift registers and latches.
A reference numeral 30 denotes a general controller (referred to hereinafter as xe2x80x9chost micomxe2x80x9d) comprised of, e.g., a host micro-computer. The host micom 30, which stores a program corresponding to the electrode structure of the VFD 10, controls the display device. For instance, the host micom 30 provides the anodes and grids of the VFD 10 with display data based on a status of a peripheral device 40. Specifically, the host micom 30 reads from a memory (not shown) therein data corresponding to characters or graphics or a combination thereof to be displayed by the VFD 10 and timely outputs the data (i.e., the display data) to the drivers 20a and 20b. 
Conventionally, the VFD 10, the anode driver 20a and the grid driver 20b are mounted on a single circuit board. It is also designed so that in addition to allowing the host micom 30 controlling the peripheral device 40, e.g., a servo motor, according to the display contents, it also allows a machine to be controlled in response to a command signal from a control panel 50.
The conventional display device described above, however, although dependent in part on the capability of the host micom 30, has difficulties in changing or modifying display contents because it has been rather difficult to change or modify the programs stored in the host micom 30, and, therefore, has found its applications to one that requires a rather small number of display contents and/or rather simple display systems. In other words, there exist limitation in the use of the conventional display system described above for various display modes thereof.
In an attempt to overcome these limitations, a modified conventional display device has been adopted as shown in FIG. 13. The modified display device of FIG. 13 is characterized in that it is additionally equipped with a sub-micom 60 between the host micom 30 and each of the anode driver 20a and the grid driver 20b compared with the display device of FIG. 12 to thereby enable it to display rather complicated display patterns and enjoy a certain degree of universality. The sub-micom 60 is additionally incorporated therein to take over functions relating to the control operations relative to the VFD 10 while the host micom 30 performs rather simple control operations and performs functions such as providing the display data for the drivers 20a and 20b. The control operations in relation to the VFD 10 include: performing control relative to a display mode from the sub-micom 60; transferring the display data associated with the display mode; maintaining the display data; and performing a signal processing and the like. With the help of this additional sub-micom 60, the host micom 30 is allowed to reduce its load significantly, thereby enabling the modified display device to display more complicated and diverse display contents.
There are, however, still certain disadvantages in the modified display device, e.g., it imposes a requirement that the sub-micom 60 and the drivers 20a and 20b closely interwork with each other. If a variety of electrode structures and/or driving methods are engaged in the modified display device, a plurality of sub-micoms corresponding to each structure and method must be employed, which exacts time and costs in designing and adapting each of the sub-micoms thereto. This may simply degenerate the desired variety and universality.
Meanwhile, an alternative controller driver may be proposed wherein a multiple number of distinct sub-micoms and the two drivers 20a and 20b are merged into an integrated circuit and the integrated circuit in turn, being connected to a couple of VFDs which are designed to accommodate a large volume of display contents corresponding to the multiple number of sub-micoms. Even in this alternative controller driver, the display capability thereof is limited to the number of combinations of the driving methods of the controller driver.
Further, it does not allow additional display modes or scan modes to be added thereto.
It is, therefore, a primary object of the present invention to solve the above described problems.
In accordance with one aspect of the present invention, there is provided a controller driver, connected to a host micom for controlling operations of a display system and to a display unit, for actuating a display unit, the controller driver comprising: an interface for transferring data from/to the host micom; a decoder for identifying and dividing the data received from the interface into command data and display data; a display RAM for storing the display data received from the decoder, wherein the display data includes anode data and grid data, the anode data being associated with display contents and the grid data being associated with a driving mode of the display unit; an electrode driver, including therein an anode driver and a grid driver, for actuating the display unit by using the command data and the display data; a controller for setting the driving mode and a display mode by using the command data, and, for retrieving the display data and providing the display data to the electrode driver; and a clock generator for providing timing signals for the interface, the decoder, the anode driver, the grid driver, the display RAM and the controller to coordinate operation timings thereof, wherein the anode data and the grid data are provided to the anode driver and the grid driver, respectively, according to a predetermined timing address.
In accordance with another aspect of the present invention, there is provided a method for driving a display device equipped with a plurality of controller drivers and a display unit, each of the controller drivers including: an interface for transferring data from/to a host computer; a decoder for decoding the data received from the interface into command data and display data; a display RAM for storing the display data received from the decoder; an anode and a grid drivers for driving a display unit based on the display data of the display RAM; a controller for setting a display mode based on the command data and for retrieving the display data corresponding to a display mode; and a clock generator for providing timing signals for the interface, the decoder, the display RAM and the controller to coordinate operation timing thereof, wherein the method comprising: connecting the plurality of controller drivers to the display unit, distributing data corresponding to display areas of the display unit and controlling operations of the plurality of controller drivers in synchronism with each other as of turning on/off the display unit.
It is possible, in accordance with the present invention, to diversify display contents by providing a display RAM storing command data and display data such that a plurality of controller drivers described above are connected to a single VFD and are controlled to operate in synchronism with each other.
The controller driver in accordance with the present invention is capable of implementing a universal driving mode of the VFD (single grid driving, dual grid driving, multi-matrix driving, etc.) and various complicated display functions without burdening the host micom. These can be achieved by synchronizing the period of a clock source for use in setting timing with an external sync signal, and, at the same time, employing a plurality of controller drivers whose number depends on the size of the VFD.